反应烧结合成O’SiAlON-BN复合材料的工艺研究

Synthesis of O’-SiAlON-BN composite by reaction sintering

以微米级αSi3N4、SiO2、Al2O3和hBN为原料,通过反应烧结法合成了O’SiAlON-BN复合材料(Si2-zAlzO1+zN2-z的z=0.3)。首先在n(SiO2)/n(αSi3N4)=1的理论配比,1700℃保温2h的条件下对比研究了Y2O3+TiO2和Y2O3+B2O3两种混合烧结助剂对该复合材料的助烧效果。结果表明:Y2O3+TiO2作为烧结助剂比Y2O3+B2O3有更好的促进烧结作用,且复合材料的相对密度随着BN(分别为10%,20%和30%)的增加而降低;XRD分析发现,αSi3N4、SiO2原料在理论配比的情况下,会导致βSi3N4相剩余,为了得到O’SiAlON和BN相含量高的复合材料,需要加入过量的SiO2。根据此研究结果,在以Y2O3+TiO2作烧结剂,BN加入量为10%的条件下,通过4因素3水平(因素水平如下:A———n(SiO2)/n(αSi3N4),取1.05、1.1、1.2;B———烧结助剂加入量,取2%、4%、6%;C———烧成温度,取1600℃、1650℃、1700℃;D———保温时间,取1h、2h、3h)的正交试验确定了影响O’SiAlON-BN复合材料烧结性能的主要因素依次为烧成温度、保温时间、烧结助剂加入量、n(SiO2)/n(αSi3N4),合成的复合材料相对密度最高的工艺参数组合为A3B3C3D3;利用统计模式识别方法对合成O’SiAlON-BN复合材料的工艺条件参数进行了优化,得到的优化区为:Y>1024X2-230.400X+11.088(其中,X=0.9999A-0.0006C-0.0163D,Y=0.0163A+0.0009B-0.0014C+0.9999D),在此优化区内,复合材料中全部为O’SiAlON和BN相,无残留βSi3N4相。

By using micron α-Si3N4, SiO2, Al2O3 and h-BN as starting materials, O＇ -SiAlON - BN （ Si2-xzAl2O1 ＋z N2-z, z=0.3） composite was synthesized by reaction sintering. According to theoretical proportion ratio： n（ SiO2 ） / n（ α-Si3 N4 ） = 1, the effects of two sintering aid composites, Y2 O3 ＋ B2 O3 and Y2 O3 ＋ TiO2 at 1700℃ for 2 h,were studied. The results indicate that Y2O3 ＋TiO2 as sintering aid can accelerate reaction sintering of O＇-SiAlON -BN composites more effectively than Y2O3 ＋ B2O3 ,and the relative density of the composites declined with the increase of BN addition（ 10% ,20% and 30% respectively） ;XRD analysis found that excessive β-Si3N4 existed in the O＇-SiAlON - BN composite. Therefore, in order to get more pure O＇-SiAlON and BN phases in the composites more SiO2 is needed. When Y2O3 ＋TiO2 was used as sintering aid and addition of BN was 10%, the result of cross experiment on condition of A-n（ SiO2）/ n（α-Si3 N4 ） was 1.05,1.1 and 1.2 ; B-addition of sintering aid was 2% ,4% and 6% ; C-firing temperature was 1600 ℃,1650℃ and 1700 ℃;D-soaking time was 1 h,2 h and 3 h,shows that the sintering properties were influenced by factors of firing temperature, soaking time, addition of sintering aid and n（SiO2）/ n（α-Si3 N4） in order of importance. In addition,the technical parameter A3 B3C3 D3 can achieve the highest relative density. Besides, using Pattern Recognition method, the optimized parameter range to form pure O＇-SiAlON and BN without β-Si3N4 remained was determined as Y 〉 1024X^2 -230. 400X ＋ 1 1. 088 （X= 0.9999A -0.0006C -0. 0163D, Y =0.0163A ＋0.0009B -0.0014C ＋0. 9999D）.